1. Field of the Invention
This invention relates to a sheet take-out apparatus that takes out accumulated sheets, for example, banknotes and the like by separating them one by one in a sheet sorting and arranging apparatus.
2. Description of the Related Art
As a sheet take-out apparatus of this type, for example, a friction type apparatus to take out sheets by a friction force of rubber rollers is known. In such a sheet take-out apparatus as this, it is demanded to be able to take out sheets by separating them surely without skewing. It is also desired that an apparatus is able to take out sheets stably without being affected by thickness and friction coefficient of sheets and further, in the case of banknotes, an apparatus is not affected by difference in kinds and sizes. On the other hand, from a viewpoint of processing capacity, an apparatus capable of taking out a large number of sheets within a unit time is desired.
As an apparatus to satisfy such demands, for example, a sheet take-out apparatus using separation rollers as disclosed in Japanese Patent Application No. 2002-53234, filed on Feb. 19, 2002 is developed. This sheet take-out apparatus comprises sending rollers to send out sheets from a supply portion, take-out rollers to take out the sheets sent out, and separation rollers kept in contact with the take-out rollers, and given with reversing torque in the direction reverse to the sheet take-out direction, separate sheets one by one.
However, this type of sheet take-out apparatus uses separation rollers that are given with a reverse torque in the direction reverse to the take-out direction of sheets and these separation rollers are worn away gradually. When the separation rollers are worn away, their diameters become small and tangential power in the reverse direction at a point where the separation rollers are in contact with the take-out rollers will become large. That is, the contacting pressure between the take-out rollers and the separation rollers decreases from a value that is optimum set for new rollers and the tangential power of the separation roller increase.
Originally, the separation rollers turn in the sheet conveying direction. However, by this change in the sheet separation condition, the number of turns decrease and the rollers are finally disabled to turn, and repeat the reversing and stopping. As a result, the number of sliding frictions generated with the separation rollers when taking out sheets will increase and the separation rollers are worn away at an accelerating pace and finally, disabled to take out sheets.